Apparatus for use in logging wells



y 1946- J. T. HAYWARD APPARATUS FOR USE IN LOGGING WELLS Filed March 15,1941 2 Sheets-Sheet 1 w wwg mw LO 0 O O O O O O O O O O O O O O O 0 O OO O O O O 0 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O Wmsk llllllll ll 9 MEQQ EN Q .16. McAsurflNu & ltSTlNG 3mm: Wu

July 16, 1946. 11 HAYWARD 2,404,132

APPARATUS FOR USE IN LOGGING WELLS Filed March 15, 1941 2 She'ets-Sheet2 VOLUME UNITS /N WELL 1' I 34 v I I TO PUMP I T J Q JOHN 7. HAYWARDuvmvm A TTORNEYS.

$13. MEASURING it TESTING Patented July 16, 1946 UNITED STATES PATENTOFFICE 11 Claims.

This invention relates to the logging of wells and particularly toapparatus for the logging of rotary drilled wells during the drillingthereof.

The Hayward Patent No. 2,214,674, dated September 10, 1940, discloses amethod for logging wells during the drilling thereof by the employmentof a circulating drilling fluid, wherein increments of the drillingfluid passing through the drilling zone and thence to the top of thewell are traced in their passage through the well by measuring the depthof the stratum being drilled at the bottom of the well in synchronismwith the rise of the increments from that stratum to the top of thewell, so that each increment of the drilling fluid reaching the top ofthe well may be correlated with that stratum responsible for thepresence in that increment of materials charac-' terizing that stratum,the increments reaching the top of the well being tested in various waysfor the presence in the fluid of such characterizing materials. In sucha method it is important that each increment tested be accuratelyrelated to the depth of the stratum to which it refers in order toobtain a true and accurate log of the several strata traversed by thewall and it is also very important that the logging take place duringthe normal course of drilling of the well in order that the driller maybe continuously apprised of the character of the strata being drilled toavoid the ever-present danger of missing strata having oil and gasproducing potentialities.

The present invention is directed particularly to improvements in theHayward method by providing improved apparatus whereby the movement ofthe drilling fluid increments may be continuously traced in theirpassage through the well and. automatically and continuously recorded ona chart which is driven in synchronism with the progressive downwardmovement of the drill in the well, and upon which the several tests ofthe emerging increments, may be continuously plotted so as to bring themin direct correlation with the depths of the strata to which they refer,to thereby eliminate much labor and to provide a greatly simplified andmore accurate log of the well continuously during the actual drillingthereof.

In accordance with the present invention, a chart bearing depth indiciais driven in synchronism with the progressive downward movement of thedrill, while a marking device such as a pen or the like is driven inaccordance with the volumetric fiow of the drilling fluid through thewell and is caused to trace or plot, on the moving chart, the passage ofthe drilling fluid through the well, or through that part of the wellextending from the drilling zone to the top of the well through theannular space between the drilling string and the wall of the well bore.

In accordance with one embodiment of this invention, starting with anygiven depth of the drilling zone, the volume of drilling fluid flowingthrough the well is continuously measured and the passage of anincrement of the drilling fluid from the drilling zone to the top of thewell is traced on the chart by causing the pen or other marking deviceto initiate a graph on the movin chart at the instant the incrementpasses 18 the drilling zone depth and then tracing the passage throughthe well of a volume of drilling fluid equal to the volumetric capacityof the annular space between the drilling string and the well bore forthat depth, the graph being caused to 20 terminate when that volume offluid has passed through the well. By this method the terminal point ofthe graph will indicate the emergence of that increment from the top ofthe well. To correlate any test made on that increment with the depth ofthe drilling zone at the time that increment passed through the drillingzone, it is only necessary to follow back along the graph to the depthon the chart opposite the point of initiation of the graph. A new graphis initiated on the chart immediately upon emergence of one volume offluid, traced as described, and additional volumes are similarlyrepeatedly traced on the moving chart to produce a continuous record ofthe entire well or any portion thereof.

The scale upon which each graph is traced is a scale composed preferablyof units of volume and the transverse width of the scale is arranged torepresent the volumetric capacity of the well or of the annular spacebetween the drilling string and the well bore, as may be desired.

Since the width of the chart covered by succeeding graphs would becomeprogressively greater as the depth of the well increased and thevolumetric capacities became proportionally greater, another embodimentof this invention provides a means whereby these graphs may be confinedwithin a chart section of fixed width, by varying the effective valuesof the volume units composing the scale upon which the graphs areplotted, in accordance with the change in the volumetric capacities ofthe well or of the annular spaced referred to.

By tracing on the same chart the records of the several tests made uponthe emerging increments of the drilling fluid, in proper relation to thedepths at which the tested increments emerge from the well, the actualdepths to which the tests refer may be read directly from the chart andthe logging operation thereby greatly simplified and made more accurate.

A still more comprehensive log of a drilling well may be made, embodyingthe apparatus of this invention, by instrumentally recording on the samemoving chart other measurements, such as drilling rate, weight on thebit, torque on the drilling string, power required per foot drilled,etc. Such measurements can be and ordinarily are made at the time theformations to which they refer are drilled, and they will, therefore,appear on the chart at the depths to which they properly refer, and canbe correlated directly with the information obtained from thecirculating fluid.

The important feature in all of these embodiments is the provision, inaccordance with this invention, of apparatus for automatically andcontinuously tracing the passage of increments of the drilling fluidthrough the well being drilled travels downwardly through the interiorof the drilling string to the drilling zone in the vicinity of the bit'I and thence upwardly through the annular space S between the drillingstring and the wall of the well bore to outlet pipe 3, which dischargesthe fluid back into pit I2 for recirculation through the well. A valvedpipe I5 provides means for withdrawing samples of the drilling fluidemerging from the well through outlet pipe 3.

A strip chart, indicated generally by the numeral I6 and of more or lessconventional form, is driven in synchronism with the progressivedownward movement of the drill bit I in the well,

being connected to the drilling string for this purpose by a drivemechanism I"I driven from the crown block III. The details of the mechona chart moving in synchronism with the r progressive downward movementof the drill in the well.

By the terms "progressive downward movement of the drill or progressivemovement of the drill downwardly in the well is meant,

movements in the well in the normal course of drilling which do notconstitute deepening of the well.

The various objects and advantages of this invention will be morereadily understood from the following detailed description when read inconjunction with the accompanying drawings which illustrate, more orless diagrammatically, apparatus suitable for practicing the methods ofthis invention. It will be understood, however,

that this invention is not limited to any particular apparatus, but thatvarious changes may be made in details within the scope of the appendedclaims, without departing from the spirit of this invention.

In the drawings:

Fig. 1 illustrates, more or less diagrammatically, an assembly ofapparatus whereby the passage of drilling fluid through a drilling Wellis traced on a chart driven in synchronism with the downward movement ofthe drill, in accordance with one embodiment of this invention.

Figs, 2 and 3 illustrate, more or less diagrammatically, some of thedetails of the apparatus shown in Fig, 1, and

Fig. 4 illustrates a portion of a chart produced in accordance with oneembodiment of this in- Vention.

Referring to the drawings and Fig. 1 in particular, there is shown awell I, having the usual surface casing 2 with a fluid outlet pipe 3con-- nected thereto. The usual drilling derrick 4 is mounted over thewell and the usual hollow drilling string 5 extends through a rotarytable 6 into the well and is provided with a bit I at its lower end anda water swivel 8 at its upper end. 1

The drilling string is operatively suspended in the well from atraveling block 9 which is swung from the usual crown block I0 by meansof cables II. Drilling fluid is circulated from the usual mud pit I2 bythe usual mud pump I3 through a pipe I4 to the swivel 8, whence thedrilling fluid anism I! for driving the chart I6 in synchronism with thedownward movement of the drill do not form a part of this invention andany suitable form of drive mechanism'may be employed for this purpose.One such mechanism is illustrated and described in detail in applicantsPatent No. 2,326,219, granted August 10, 1943. As stated, however, anyother suitable drive mechanism may be employed, it being important onlythat the chart I6 be caused to move thereby in synchronism with theprogressive downward movement of the drill. The chart I 6 is driven atany suitable rate such as, for example, one inch foreach fifty feet ofdownward progress of the drill.

The drilling fluid being pumped through the well is metered in anysuitable way, as by means of a meter I8 mounted in pipe I4, or if pumpI3 is of a conventional positive displacement type, it may be employedas a meter for this purpose by suitably connecting thereto a counter I9to count the stroke cycles of the pump in a manner well understood inthis art. The counter I9 may, accordingly, be calibrated to read eitherunits of volume or simply stroke cycles, since with this type of pump,the stroke cycles bear a definite relationship to the volume of fluidpumped, and the number of stroke cycles is equally suitable for thepurpose of this invention for measuring the volume of fluid circulatedthrough the well,

The fluid meter, whether meter [8 or counter which is adapted totelemetrically drive a mark- 7 ing device 2I, such as a pen or the like,conventionally used with recorders of the type illustrated generally,which traces a record of the passage of drilling fluid through the wellon the moving chart I6, in a manner to be more fully describedhereinafter.

The mechanism 20 is illustrated more specifically in Figs. 2 and 3. Thefluid meter I8 or counter I9, for example, drives a splined shaft 22 onwhich is slidably keyed a disk 23,.the rim of which frictionally engagesthe face of a larger circular plate 24 positioned at right angles todisk 23. Plate 24 is firmly aiiixed to an axial shaft 25 mounted inbearings 26, plate 24 and shaft 25 being rotatable togetherin bearings26 by the frictional drive imparted thereto from disk 23. The free endof shaft 25 is drivingly connected to the contact arm 21 of aconventional potentiometer 28 to cause the arm 21 to rotate upon acircular resistor 29 (Fig. 3) which is connected in a conventionalcircuit with a battery 30. The contact arm 21 andresistor 29 areconnected by conductors 3|-32 to a conventional recording potentiometer33a which operates the pen 2| in the conventional manner for electricalrecorders, as is well understood by those skilled in the art of thesedevices. The pen 2| is thus made responsive to the movement of fluid asmeasured by counter I0, to trace on the moving chart l6 a plurality ofgraphs G, G1, G2, etc. (Fig. 4), each representing the passage throughthe well of a volume of fluid equal to the volumetric capacity of thewell or of annular space S.

The arrangement of disk 23 on plate 24 constitutes a variable gear ratioconnecting shafts 22 and 25, whereby the ratio of the speed of shaft 22to that of shaft 25 may be varied by varying the radial position of thepoint of contact of disk 23 with plate 24 relative to the center of thelatter. Thus if shaft 22 makes one revolution for each unit accumulatedin counter l9, and it is desired to make plate 24 and shaft 25 rotateonce for a selected number of units accumulated in counter l9, this maybe readily accomplished by selecting a suitable point of contact onplate 24 for disk 23. For this purpose, disk 23 is movablelongitudinally along splined shaft 22 by means of an arm 33 which isprovided with a pointer 34 which travels along a scale 35 calibrated inunits of volumetric capacity of the well. Arm 33 travels along a bracket36 and is provided with a latch 31 for looking it to the bracket inorder to fix the position of disk 23 on plate 24 in accordance with thegear ratio required as determined in terms of the units of scale 35. Theunits of scale 35 are preferably, though not necessarily, the same asthose accumulated in counter l9.

In using this portion of the apparatus, we may assume for purposes ofillustration, that the volumetric capacity of annular space S is 500units of volume. These units may be barrels, gallons, cubic feet, pumpcycles, or any other suitable unit. It is desired that the pen 2| makeonly a single trace across the chart I6 during the passage of a volumeof fluid equal to the volumetric capacity of the annular space S andthen return to its initial position. The pointer 34 is set at the figure500 on scale 35, it having been previously determined that at thatsetting every time 500 units is accumulated in counter I9; thecorresponding number of rotations of disk 23 will cause plate 24 to makeone complete revolution and this in turn will operate potentiometers 28and 33a to drive pen 2| across a chart a distance representing thevolumetric capacity of annular space S. Completion of a rotation of arm21 on resistor 29 will operate in the conventional manner to reset pen2| in its initial position. As the volumetric capacity of space Sincreases with increasing depth of the well, the position of disk 23 onplate 24 is reset in accordance with the correspondingly increasednumber of units required to equal this increased capacity. But shaft 25will still make only one revolution despite the increased number ofrevolutions required of disk 23. As a result, the width of the scale,that is, the transverse distance over which pen 2| will be driven willremain fixed, the effect of the change in the ratio between the speedsof shafts 22 and 25 being only to change the value of the volume unitscomposing the scale on which the graphs G, G1, etc. are plotted. As aresult, the initial and terminal points of each of the graphs will fallon two parallel lines marking the borders of the scale and therebypermit the use of a limited section of the chart for tracing the passageof successive volumes of the drilling fluid through the well,irrespective of any variations in these volumes due to changes in depthof the well.

It will be obvious that any suitable or conventional form of variablegear ratio may be substituted for the elementary form including disk 23and plate 24 described above.

It will also be understood that where chart space is not a factor,apparatus for mechanically changing the value of the scale units overwhich pen 2| moves is not necessary and the graphs G, G1, etc. may havedifierent lengths corresponding to the particular volumes theyrepresent, it being only necessary to provide more or less conventionalmeans in the recorder mechanism for homing the pen after each volume offluid, corresponding to a particular depth, has flowed from the well. Itwill also be understood that various conventional recording mechanismsmay be employed for operating the pen, either in a series of strokes allbeginning at one side of the chart or passing back and forth across thechart with the passage of consecutive volumes of the fluid, all withoutdeparting from the principles or the spirit of this invention.

The complete apparatus above described is employed in the followingmanner:

For the purposes of this description, counter I9 will be employed, itbeing understood that meter I8 or any other suitable fluid meteringdevice may be readily substituted therefor, if desired, without alteringthe principles of the new method. We will assume, for purposes ofillustration, that the drill is at a depth of 3000 feet, although itwill be evident that the method can be employed from start to finish ofthe drilling of the well or for any section thereof as may be desired.Since the depth is known, as are the diameters of the well and of theoutside and inside of the drilling string 5, the volumetric capacity ofthe well and of the annular space S can be readily determined for anydepth, either by computation or by experimental methods well understoodin the art. From these determinations, it can readily be computed howmany units must be recorded on counter l9 to represent the passagethrough v the well of a volume of fluid equal to the volumetric capacityof the well, or of annular space S. For convenience, the latter figureis ordinarily employed, since it is usually desired to trace themovements of increments of the drilling fluid from the drilling zone atthe bottom of the well to the top of the well. The total well capacitycan also be employed for this purpose by applying to each reading acorrection factor corresponding to the volumetric capacity of the hollowdrilling string for that depth. Mechanism 20 is then adjusted so that itwill cause pen 2| to move once across the chart while that number ofunits is recorded on counter l9 which represents the passage through,the well of a volume of fluid equal to the volumetric capacity ofannular space S for a depth of 3000 feet. The well is filled with fluidand drilling is begun at the same time that circulation of the drillingfluid is started. At the same time, pen 2| will be started on the chartH5 at a point along the depth scale of the chart opposite the figure3000 and will make its initial impression in (Fig. 4) at that point.This initial impression to will represent the position of an incrementof the drilling fluid at the bottom of the well, namely, at a depth of3000 feet. Now as the drilling and cir- IIVVIII culation of the drillingfluid continue, pen 2| will be actuated by counter I9 operating throughthe mechanism 20 to move across chart IS in accordance with thedisplacement of the increment of the drilling fluid upwardly from thebottom of the well through the annular space S and the changing positionof the pen will continuously indicate the changing position of theincrement relative to the bottom of the well by drawing the graph G.When counter l9 has recorded the passage of the pre-determined number ofunits, the increment will be emerging from the top of the well and pen2| will make a final impression g on the chart indicating that point,and by the homing action of the mechanism 20, the penis then caused toswing back to the opposite side of the chart and initiate a new graph G1tracing the movement of a succeeding volume of fluid through the well.However, during the time required for the increment to move from thebottom to the top of the well, the drill bit I will have progressed somedistance below the original 3000 foot depth by a variable distancedepending upon the relative hardness of the formations, the rate ofdrilling, etc. Chart IE will have moved longitudinally a correspondingdistance, as a result of which the right hand end of the graph G willappear on the chart opposite some depth figure greater than 3000 feet,

say 3020 feet. A test taken of the increment of the fluid emerging fromthe well and recorded on the chart at that time will, therefore, appearat the greater depth. However since the graph G now connects the initialand final points a: and y, it is only necessary to follow the graph backfrom y to a: to determine the true depth to which the test taken at yactually refers.

Fig. 4 illustrates a, portion of a chart, made in accordance with thisinvention, bearing a plurality of successive graphs G, G1, G2, G3, etc.,representing the passage of a plurality of successive increments of thedrilling fluid from the bottom to the top of the well. The initialpoints of each of these graphs appear opposite a depth figure whichrepresents the depth of the well at the time each of the incrementsstarted from the bottom of the well, while the opposite ends of eachgraph appear at some greater depth. Of

course, since the graphs represent consecutive volumes of fluid, the endof one graph will coincide with the beginning of the next succeedinggraph relative to a depth position recorded on the depth scale. Thatdepth will be the depth at which the preceding increment emerges fromthe well as a new increment represented by the second graph begins itspassage up the well from that depth. Records of the tests made for oiland gas on the emerging increments of the drilling fluid comprise thetraces O and H, respectively, drawn on the chart in parallel columnsadjacent the terminal ends of the graphs G, G1, etc., since these testsare necessarily made on the emerging increments. Thus, in order to findthe true depth of an all show which appeared, for example, at O1opposite a depth of 3072 feet, which is the depth at which graph G3terminates, it is only necessary to follow this graph back to the pointof its initiation to find that the increment tested for oil at 01 leftthe bottom of the well at 3045 feet.

With an apparatus of logging in accordance with this invention, it isnot necessary that the test of the emerging drilling fluid fall exactlyopposite the terminus of one of the graphs G, G1, etc., in order todetermine the actual depth to which that test refers. For example,suppose it is desired to find the true depth to which a test 02 refers,which is taken on the emerging fluid when the depth of the well is 3135feet. This test falls on chart l6 between two of the graphs Gs and G7and no graph appears on the chart by which the true depth can bedirectly located. However, the true depth can be located from the chartby drawing a horizontal line corresponding to the depth of 3135 feetopposite 02 until it strikes the graph G7. From the point ofintersection with G7 a line is drawn vertically until it intersects thegraph G6, whence a horizontal line is drawn to intersect the depth axis,giving the true depth of about 3122 feet as the depth of the well whenthe tested fluid left the, bottom. By means of the chart, produced bythe apparatus of this invention, the emerging fluid can be tested at anytime and the test referred directly to the true depth which itrepresents.

It will be obvious that, as the volumetric capacity of the well and ofspace S increases with increasing depth, graphs G, G1, etc., willnormally lengthen correspondingly. However, by the provision of a scalechanging device such as mechanism 20, the graphs will all be confinedwithin a strip on the chart of fixed width, irrespective of the changesin volume and without affecting the accuracy of the record.

By logging wells in the manner described, various logging tests may beplotted on the same chart and all the various characteristics of theformations penetrated by the drill, as determined for logging purposes,will appear directly on the chart in properly correlated relationship.For example, referring to Fig. 4, the drilling rate is continuouslytraced in a graph D along side the depth index. Since this graph isordinarily obtained from the mechanical reactions of the drill as itprogresses through the earth strata, its values will appear directlyopposite the true depths to which these these values refer. Traces O andH, which represent the values of oil and gas, respectively, in theemergin drilling fluid, will appear, as shown, opposite the depths atwhich the tested increments of the drilling fluid emerge, but aspreviously described, by means of the graphs G, G1 G2, etc. These valuescan be directly correlated with the true depths and with thecorresponding values of the drilling rates, at each of these depths, andthe drilling rates, therefore, become of special value as an additionalcheck of the oil and gas strata, since these are normally softer thanother adjacent strata and are generally clearly evidenced in thedrilling rate graph. The traces of the Drilling Rate and of Oil and Gasmay be placed on the record in any suitable manner.

It is ordinarily not necessary to continuously change the scalerepresenting the volumetric capacity as the depth changes, although thismay be done if desired. Usually, the scale is changed at some suitableinterval of increasing depth, such as at every 20 feet or every 50 feet,or at any other suitable interval, depending upon the depth of the well.For example, if a well is drilling at 3000 feet, an increase in depth ofas much as 30 feet will produce a change in volumetric capacity of thewell of only one percent, and since the fluid circulates at high rates,often as much as several hundred barrels per foot drilled, the resultingerror in correlating the tests of the outgoing fluid with the true depthwill ordinarily be only a small fraction of one percent, which is a veryhigh degree of accuracy.

From the foregoing it will be evident that this invention providesapparatus by which a complete and accurate log may be made continuouslyduring the rotary drilling of a well.

What I claim and desire to secure by Letters Patent is:

1. An apparatus for logging the strata of a well while being drilled bythe employment of a hollow rotary drill string and a fluid circulateddown said string and up outside thereof to the surface, comprising, thecombination with means cooperating with the drill string for measuringthe depth of a stratum being drilled, of means cooperating with thedepth measuring means for measuring the rise ofa selected increment ofthe fluid from said stratum.

2. An apparatus for logging the strata of a well while being drilled bythe employment of a hollow rotary drill string and a fluid circulateddown said string and up outside thereof to the surface, comprising, thcombination with chart means driven by said drill string to move insynchronism with the progressive downward movement thereof through saidstrata, of means for measuring the volume of said fluid flowing throughthe well, and marking means cooperating with said measuring means fortracing on the moving chart the records of the rise of selectedincrements of said fluidfrom each of said strata to the surface.

3. In combination with rotary well drilling apparatus includin a hollowrotary drill string and means for circulating drilling fluid through thewell, depth recording means driven by said drill string to move insynchronism with the progressive downward movement of said drill string,means for measuring the vol me of drilling fluid flowing through thewell, mar ing means operatively associated with said recording means andresponsive to the flow of the drilling fluid through said measuringmeans to plot on said recordin means the record of the passage of saidfluid through the well relative to the changing depth thereof,

4. In combination with rotary well drilling apparatus including a hollowrotary drill string and means for circulating drilling fluid through thewell, depth recording means driven by said drill string to move insynchronism with the progressive downward movement of said drill string,means for measuring the vol of drilling fluid flowing through the well,marki g means operatively associated with said recording means andresponsive to the flow of the drilling fluid through said measuringmeans to plot on said recording means the record of the passage of saidfluid through the well relative to the changing depth thereof, andlimiting means operatively associated with said marking means andresponsive to the passage of a pre-determined volume of said fluidthrough said measuring means to correspondingly limit the total distancemoved by said marking means relative to said recording means.

5. In combination with rotary well drilling apparatus including a hollowrotary drill string and means for circulating drilling fluid through thewell, depth recording means driven by said drill string to move insynchronism with the progressive downward movement of said drill string,means for measuring the volume of drilling fluid flowing through thewell, marking means having a variable ratio drive connection with saidmeasuring means and respo sive to the flow of the drilling fluid throughsai \measuring means to plot on said recording means the record of thepassage of said fluid through the well relative to the changing depththereof, and

limiting means operatively associated with said marking means andresponsive to the passage of a pre-determined volwfle of said fluidthrough said measuring means to correspondingly limit the total distancemoved by said marking means relative to said recording means, said driveconnection including means for varying the drive ratio between saidmeasuring means and said marking means in proportion to changes in saidpre-determined volumes.

6. In combination with rotary well drilling apparatus including a hollowrotary drill string and means for circulating drilling fluid through thewell, depth recording means driven by said drill string to move insynchronism with the progressive downward movement of said drill string,means for measuring the vol of drilling fluid flowing through said well,marking means operatively associated with said recording means andresponsive to the flow of fluid through said measuring means tosuccessively plot on said recording means relative to the changing depthof the well the records of the passage of successive pre-determinedvolumes of said fluid through said well.

7. In combination with rotary well drilling apparatus including a hollowrotary drill string and means for circulating drilling fluid through thewell, depth recording means driven by said drill string to move insynchronism with the progressive downward movement of said drill string,means for measuring the volume of drilling fluid flowing through saidwell, marking means having a variable ratio drive connection with saidmeasuring means and responsive to the flow of fluid through saidmeasuring means to successively plot on said recording means relative tothe changing depth of the well the records of the passage of successivepre-determined volumes of said fluid through the well, and limitingmeans operatively associated with said marking means and responsive tothe passage of each of said pre-determined vol es of said fluid throughsaid measuring cans, to limit in proportion to each of saidpre-determined volumes the distance moved by said marking means relativeto said recording means, said limiting means including means for varyingthe drive ratio of said drive connection between said measuring meansand said marking means in proportion to changes in said pre-determinedvolumes, to thereby uniformly limit said distance moved by said markingmeans for all of said volumes.

8. In combination with a, well being drilled by the employment of ahollow rotary drill string and a fluid circulated down said string andup outside thereof to the surface, apparatus for plotting the passage ofincrements of said fluid through said well relative to the changingdepth of the well, comprising, a chart driven by said drill string tomove in one direction in synchronism with the progressive downward movement of said drill string, said chart bearing a scale of depthmeasurement extending in said direction, means for circulating saidfluid through the ell, measuring means for measuring the voluxfil offluid passing through the well, marking eans responsive to the flow ofthe fluid through said measuring means to move across said chartgenerally transversely relative to the direction of movement of saidchart from a point along said depth scale corresponding to the bottom ofthe well, drive means operatively connecting said measuring means tosaid marking means and including means for terminating the transversemovement of said marking means upon passage through the well of apredetermined volume of the fluid required to displace an incrementthereof from the bottom of the well to the surface, and for theninitiating a new transverse movement for the next succeeding increment.

9. In combination with a well being drilled by the employment of ahollow rotary drillstring and a fluid circulated down said string and upoutside thereof to the surface, apparatus for plotting the passage ofincrements of said fluid through the well relative to the changing depthof the well, comprising, a chart driven by said drill string to move inone direction in synchronism with the progressive downward movement ofsaid drill string, said chart bearing a scale of depth measurementextending in said direction, means for circulating said fluid throughthe well, measuring means for measuring the volume of fluid passingthrough said Well, marking means responsive to the flow of said fluidthrough said measuring means to draw a series of lines across said chartin a direction generally transverse relative to the direction ofmovement of said chart and initiated from a plurality of points alongsaid depth scale, each of said lines tracing the passage ofa'pre-determined volume of said fluid required to displace an incrementof the fluid to the surface from the depth represented by the point ofinitiation of that particular line, drive means connecting saidmeasuring means to said marking means and operative to cause the latterto initiate each of said lines at a point along said depth scalecorrespondingto the end of the next succeeding line.

10. In combination with a well being drilled by the employment of 3 ahollow rotary drill string and a fluid circulated down said string 12and up outside thereof to the surface, apparatus for plotting thepassage of increments of said fluid through the well relative to thechanging depth of the well, comprising, a chart driven by said drillstring to move in one direction in synchronism with the progressivedownward movement of said drill string, said chart bearing a scale ofdepth measurement extending in said direction, means for circulatingsaid fluid through the well, measuring means for measuring the volume offluid passing through said well, marking means responsive to the flow ofsaid fluid through said measuring means to draw a series of lines acrosssaid chart in a direction generally transverse relative to the directionof movement of said chart and initiated from a plurality of points alongsaid depth scale, each of said lines tracing the passage of apre-determined volume" of said fluid required to displace an incrementof the fluid to the surface from the depth represented by the point ofinitiation of that particular line, drive means connecting saidmeasuring means to said marking means and operative to cause the latterto initiate each of said lines at a point along said depth scalecorresponding to the end of the next succeeding line, said drive meansincluding a variable gear ratio means for varying the drive ratiobetween said measuring means and said marking means in proportion to thechange in volume of said well due to the change in depth thereof.

11. Apparatus for measuring and recording vnlume's' of well-drillingfluid circulating down a" drill string and upwardly outside thereof, comprising, a fluid flow meter, a recorder having cooperating elements oneof which is synchronized with the drill string, and a variable gearratio for driving the other element of said recorder from 40. the flowmeter.

JOHN T. HAYWARD.

